selftests/mm: create uffd-common.[ch]

Move common utility functions into uffd-common.[ch] files from the
original userfaultfd.c.  This prepares for a split of userfaultfd.c into
two tests: one to only cover the old but powerful stress test, the other
one covers all the functional tests.

This movement is kind of a brute-force effort for now, with light
touch-ups but nothing should really change.  There's chances to optimize
more, but let's leave that for later.

Link: https://lkml.kernel.org/r/20230412164241.328259-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/testing/selftests/mm/uffd-common.h

@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Userfaultfd tests common header
+ *
+ * Copyright (C) 2015-2023  Red Hat, Inc.
+ */
+#ifndef __UFFD_COMMON_H__
+#define __UFFD_COMMON_H__
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <time.h>
+#include <signal.h>
+#include <poll.h>
+#include <string.h>
+#include <linux/mman.h>
+#include <sys/mman.h>
+#include <sys/syscall.h>
+#include <sys/ioctl.h>
+#include <sys/wait.h>
+#include <pthread.h>
+#include <linux/userfaultfd.h>
+#include <setjmp.h>
+#include <stdbool.h>
+#include <assert.h>
+#include <inttypes.h>
+#include <stdint.h>
+#include <sys/random.h>
+
+#include "../kselftest.h"
+#include "vm_util.h"
+
+#define UFFD_FLAGS	(O_CLOEXEC | O_NONBLOCK | UFFD_USER_MODE_ONLY)
+
+#define _err(fmt, ...)						\
+	do {							\
+		int ret = errno;				\
+		fprintf(stderr, "ERROR: " fmt, ##__VA_ARGS__);	\
+		fprintf(stderr, " (errno=%d, @%s:%d)\n",	\
+			ret, __FILE__, __LINE__);		\
+	} while (0)
+
+#define errexit(exitcode, fmt, ...)		\
+	do {					\
+		_err(fmt, ##__VA_ARGS__);	\
+		exit(exitcode);			\
+	} while (0)
+
+#define err(fmt, ...) errexit(1, fmt, ##__VA_ARGS__)
+
+/* pthread_mutex_t starts at page offset 0 */
+#define area_mutex(___area, ___nr)					\
+	((pthread_mutex_t *) ((___area) + (___nr)*page_size))
+/*
+ * count is placed in the page after pthread_mutex_t naturally aligned
+ * to avoid non alignment faults on non-x86 archs.
+ */
+#define area_count(___area, ___nr)					\
+	((volatile unsigned long long *) ((unsigned long)		\
+				 ((___area) + (___nr)*page_size +	\
+				  sizeof(pthread_mutex_t) +		\
+				  sizeof(unsigned long long) - 1) &	\
+				 ~(unsigned long)(sizeof(unsigned long long) \
+						  -  1)))
+
+/* Userfaultfd test statistics */
+struct uffd_stats {
+	int cpu;
+	unsigned long missing_faults;
+	unsigned long wp_faults;
+	unsigned long minor_faults;
+};
+
+struct uffd_test_ops {
+	void (*allocate_area)(void **alloc_area, bool is_src);
+	void (*release_pages)(char *rel_area);
+	void (*alias_mapping)(__u64 *start, size_t len, unsigned long offset);
+	void (*check_pmd_mapping)(void *p, int expect_nr_hpages);
+};
+typedef struct uffd_test_ops uffd_test_ops_t;
+
+extern unsigned long nr_cpus, nr_pages, nr_pages_per_cpu, page_size, hpage_size;
+extern char *area_src, *area_src_alias, *area_dst, *area_dst_alias, *area_remap;
+extern int mem_fd, uffd, uffd_flags, finished, *pipefd, test_type;
+extern bool map_shared, test_collapse, test_dev_userfaultfd;
+extern bool test_uffdio_wp, test_uffdio_minor;
+extern unsigned long long *count_verify;
+extern volatile bool test_uffdio_copy_eexist;
+
+extern uffd_test_ops_t anon_uffd_test_ops;
+extern uffd_test_ops_t shmem_uffd_test_ops;
+extern uffd_test_ops_t hugetlb_uffd_test_ops;
+extern uffd_test_ops_t *uffd_test_ops;
+
+void uffd_stats_report(struct uffd_stats *stats, int n_cpus);
+void uffd_test_ctx_init(uint64_t features);
+void userfaultfd_open(uint64_t *features);
+uint64_t get_expected_ioctls(uint64_t mode);
+void assert_expected_ioctls_present(uint64_t mode, uint64_t ioctls);
+int uffd_read_msg(int ufd, struct uffd_msg *msg);
+void wp_range(int ufd, __u64 start, __u64 len, bool wp);
+void uffd_handle_page_fault(struct uffd_msg *msg, struct uffd_stats *stats);
+int __copy_page(int ufd, unsigned long offset, bool retry);
+int copy_page(int ufd, unsigned long offset);
+void *uffd_poll_thread(void *arg);
+
+#define TEST_ANON	1
+#define TEST_HUGETLB	2
+#define TEST_SHMEM	3
+
+#endif